If (x + 1/x)² = 3, then the value of (x^72 +x^66 + x^54+ x^24+ x^6 + 1) is

asked by guest
on Jan 22, 2025 at 1:49 am



You asked:

Given \({\left( x + \frac{1}{x} \right)}^{2} = 3\) evaluate the expression \({x}^{72} + {x}^{66} + {x}^{54} + {x}^{24} + {x}^{6} + 1\).

MathBot Answer:

\(x^{72} + x^{66} + x^{54} + x^{24} + x^{6} + 1 \in \left\{1 + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{66} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{54} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{24} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{6} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{72}, 1 + \left(- \frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{72} + \left(- \frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{6} + \left(- \frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{54} + \left(- \frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{24} + \left(- \frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{66}, 1 + \left(\frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{66} + \left(\frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{6} + \left(\frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{54} + \left(\frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{24} + \left(\frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{72}, 1 + \left(\frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{72} + \left(\frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{54} + \left(\frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{24} + \left(\frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{6} + \left(\frac{\sqrt{3}}{2} + \frac{i}{2}\right)^{66}\right\}\)


\(i\) is the imaginary unit, defined as \(i^2 = -1\).

By substituting this value into the expression, we find that: $$\begin{aligned}x^{72} + x^{66} + x^{54} + x^{24} + x^{6} + 1 &= 1 + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{66} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{54} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{24} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{6} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{72}\\&= 1 + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{66} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{54} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{24} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{6} + \left(- \frac{\sqrt{3}}{2} - \frac{i}{2}\right)^{72}\end{aligned}$$